1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to digital rights management (DRM) and, more particularly, to implementing a plurality of DRM systems in a low-efficiency storage device.
2. Description of the Related Art
Recently, research into DRM has been actively conducted, and commercial services to which DRM is applied have been introduced or are being introduced. DRM is a technological concept for protecting digital content, which is easy to illegally copy and distribute.
Although efforts to protect digital content have been made in the past, these efforts are however based on the prevention of illegal access to the digital content.
For example, access to the digital content is permitted only to users who have paid for it, and users who have not paid for it cannot access the digital content. However, due to the characteristics of digital data, the digital content can be easily reused, processed, duplicated, and distributed.
Accordingly, when the users, who have paid for and gained access to the digital content perform illegal duplication or distribution of the digital content, users who have not paid for the digital content can also use it.
In order to solve the problem, DRM allows digital content to be encrypted and distributed, and requires a license, called a Rights Object (RO), to use the encrypted digital content.
The concept of a related art DRM environment is described in detail with reference to FIG. 1 below.
Referring to FIG. 1, a device 110 can acquire digital content from a content provider 120. In this case, the digital content supplied by the content provider 120 is encrypted, and an RO is necessary to use the encrypted digital content.
The device 110 can acquire the RO, in which a right to use encrypted digital content is included, from an RO issuance authority 130. For this purpose, a user must make a predetermined payment for the digital content. The RO includes a key which enables the decryption of the encrypted digital content.
The RO issuance authority 130 reports the details of the issuance of the RO to the content provider 120. The RO issuance authority 130 and the content provider 120 may be the same entity according to the circumstances.
The device 110, which has acquired the RO, can use the decrypted digital content by consuming the RO.
The encrypted digital content may be uninterruptedly duplicated and distributed by another device (not shown). However, information about restrictions, such as the number of times of use or a period during which the encrypted digital content can be used, and the allowable number of duplications of the RO, are included in the RO, so that the RO is subjected to restrictions in the reuse or the duplication thereof, unlike the encrypted digital content. According to such DRM technology, the digital content can be effectively protected.
Furthermore, the device 110 may manage the encrypted digital content or the RO through a specific embedded system (hereinafter referred to as a ‘high-efficiency storage device’), such as a Personal Computer (PC) or a mobile phone, in which multiple processes are supported in order to make it convenient to store and distribute the RO, which is shown in FIG. 2.
Referring to FIG. 2, a host device 210 corresponds to the device 110 shown in FIG. 1, and a high-efficiency storage device 250 provides a function of managing the digital content or the RO possessed by the host device 210.
In this case, the host device 210 includes a plurality of DRM systems, such as a Microsoft DRM system and an Open Mobile Alliance (OMA) DRM system. The DRM systems may simultaneously operate through multi-tasking. Hereinafter, a plurality of DRM systems having different DRM technologies are indicated by ‘DRM system A,’ ‘DRM system B,’ and the like to identify the respective DRM technologies.
Furthermore, the high-efficiency storage device 250 may perform some of the functions of the plurality of DRM systems included in the host device 210, such as functions to store DRM-related data, an RO, or digital content. In this case, multiple processes or multi-threaded processes are performed, as in the host device 210, in order to share the functions of the plurality of DRM systems that operate through multi-tasking in the host device 210.
The DRM system A of the host device 210 assigns process A to the high-efficiency storage device 250 to store and manage data about the DRM system A in the high-efficiency storage device 250, and communicates with the high-efficiency storage device 250. At the same time, the DRM system B assigns process B to the high-efficiency storage device 250 to store and manage data about the DRM system B in the high-efficiency storage device 250 in the same manner, and communicates with the high-efficiency storage device 250. In the same manner, N processes, which correspond to N DRM systems that simultaneously operate in the host device 210, are assigned to the high-efficiency storage device 250, and are simultaneously executed.
The high-efficiency storage device 250 may include the software architecture shown in FIG. 3, so that the N processes can be assigned.
Referring to FIG. 3, the high-efficiency storage device 250 includes a process management layer, which enables it to perform scheduling on respective processes (process A, process B, . . . ). In this case, the term ‘scheduling’ refers to planning and implementing a policy for assigning processes to a Central Processing Unit (CPU) or various processors in order to process tasks.
That is, the processes may be executed by using a preemptive technique or a non-preemptive technique, and the process management layer may perform inter-process scheduling using the preemptive technique or the non-preemptive technique. In this case, the term ‘preemptive technique’ refers to a technique in which, when a single process occupies the CPU, another process can take the CPU, and the term ‘non-preemptive technique’ refers to a technique in which, when a process occupies the CPU, another process cannot take the CPU until the processing of the initial process is finished.
Recently, in order to conveniently keep and distribute the encrypted digital content or the RO, the realization of a technology that allows the digital content or the RO to be managed through a mobile storage device, such as a memory stick or a Multi-Media Card (MMC), has been attempted.
However, in the mobile storage device, the operational capability thereof is very low compared with that of the high-efficiency storage device. Only a very small amount of resources are generally assured, and a minimum amount of resources are provided for economic reasons, such as price. Accordingly, the method of installing the process management layer shown in FIG. 3 in the mobile storage device is not a desired method to support the plurality of DRM systems shown in FIG. 2.
Accordingly, even for a low-efficiency mobile storage device, a method of efficiently implementing a plurality of DRM systems is required.